Menstruation

About half the GLP-1 audience is women, but most trackers ignore that the menstrual cycle changes how the body responds to almost everything — appetite, water retention, insulin sensitivity, mood. This system tracks your cycle and feeds it into the simulation.

What you'll see

If menstruation is enabled, the Log page shows a small banner with:

• Current cycle day (e.g., "Cycle day 14").
• Current phase (menstrual / follicular / ovulation / luteal).
• Days until next period (countdown).

The banner replaces a generic "today's date" header on the Log page when the feature is on.

Setup

1. Profile → Settings → Tracking → Menstruation.
2. Enable.
3. Enter:
   • Last period start — first day of your most recent period.
   • Cycle length — how many days between starts. Default 28; the app accepts 20–45.
   • Period length — how many days you bleed. Default 5; range 1–10.
   • Luteal phase length — second half of cycle. Default 14; range 10–20.
4. Save.

You don't need to be perfectly regular. The app uses your average cycle length as a baseline; if you're irregular (PCOS, perimenopause, post-partum), the math gracefully handles cycles that land 7+ days early or late.

Logging a new period

When your period starts:

1. Log page → cycle banner → Start period today (or pick a different date).
2. The app updates "last period start" and recomputes everything downstream.

The "Start period" option only appears in plausible windows — within ~7 days of the expected next period, or when you have no anchor yet. The mid-follicular window hides it (a fresh start there isn't biologically plausible).

Phase math

The four phases are defined relative to your cycle:

• Menstrual — days 1 through your period length (default: days 1–5).
• Follicular — period end through ovulation−1.
• Ovulation — a 3-day window centered on cycleLength − lutealPhaseLength. For a 28-day cycle with 14-day luteal, that's days 13–15.
• Luteal — ovulation+2 through end of cycle.

If your cycle runs over its expected length, the math wraps — cycle day 32 of an "expected 28" cycle is treated as day 4 of the next.

Predictions

The app predicts:

• Next period date = anchor + cycle length, advancing if past.
• Next ovulation date = next cycle start + (cycleLength − lutealPhaseLength).

These are just averages projected forward. They're not contraception-grade. If you're tracking for fertility purposes, use a dedicated tool with temperature, cervical mucus, and LH testing.

Notifications

If notifications are enabled, the app can alert you a configurable number of days before your next period:

1. Profile → Notifications → Cycle.
2. Toggle on.
3. Pick lead time (default: 2 days before).

The reminder fires once per cycle.

How cycle affects the simulation

The simulation reads:

• Sex = female, and
• Menstruation enabled, and
• Last period start + cycle length + luteal length.

From those, it computes your current cycle day and phase, and applies phase-specific adjustments:

• Insulin sensitivity — varies across the cycle (typically higher follicular, lower luteal).
• Cortisol baseline — shifts with hormonal context.
• Glucose disposal — affected by progesterone in luteal.
• Water retention — predictable luteal effect.

Concrete example: a fixed-calorie day late luteal vs early follicular produces different predicted glucose and insulin responses. The dashboard chart will show the difference if you compare.

Common reactions

"My cycle is wildly irregular — does this still work?" The app uses your provided cycle length as a baseline but doesn't punish irregularity. If you get a period 35 days into a 28-day cycle, log the new start; the cycle resets. The simulation uses whatever the current cycle's anchor and length are.

"I'm post-menopausal." Disable menstruation. The simulation handles post-menopausal physiology when sex=female and menstruation is off.

"I'm on hormonal contraception or HRT." This complicates things. If your contraception suppresses ovulation entirely (most combined pills, hormonal IUDs after a few months), turning menstruation off and tracking hormones in Bloodwork is more accurate. If you have breakthrough bleeding patterns that approximate a cycle, you can track them, but understand the model is fitting to apparent cycle phases that may not reflect underlying physiology.

"I want to track period symptoms specifically." Add custom symptoms: "cramping," "PMS mood," "breast tenderness," etc. They'll show up alongside everything else in the symptom log.

Privacy

Cycle data is sensitive personal data. Stored encrypted, against your account only, never used in cross-user analytics. Included in export and removed on deletion.

Related

• Bloodwork — for tracking cycle hormones (estradiol, progesterone, LH, FSH).
• Conditions — PCOS specifically interacts with cycle math.
• Endogenous simulation — phase effects on the model.